The Food and Drug Administration recently approved imatinib (Gleevec) to prevent the regrowth of gastrointestinal stromal tumor, a rare form of cancer, after its surgical removal. Imatinib is already approved for the treatment of Philadelphia chromosome- positive myeloid leukemia and myelodysplastic-myeloproliferative diseases associated with platelet-derived growth factor receptor gene rearrangements in adult patients, as well as other types of cancer. It is an inhibitor of the receptor tyrosine kinases for platelet-derived growth factor and stem cell factor that inhibits the growth of certain cell lines by blocking the communication between cells.

When used for this new indication, the drug's adverse effects are comparable to those seen with its use in treating other forms of cancer-diarrhea, fatigue, nausea, peripheral edema, anemia, rash, vomiting, and abdominal pain. Serious adverse effects, such as hemorrhage and, occasionally, significant edema, are possible with its use for any clinical indication. Drug interactions through the cytochrome P-450 (CYP) isoenzyme system are likely because imatinib is metabolized by CYP3A4 and inhibits the activity of CYP2D6, and the drug also increases the circulating level of acetaminophen. Nurses should monitor patients closely for bleeding and signs of congestive heart failure (caused by pulmonary edema). They should also confirm by using a drug database that any other drug therapy prescribed is not known to interact with imatinib through the CYP isoenzyme system.

Novartis Pharmaceuticals Corp. Gleevec (imatinib mesylate) tablets for oral use. 2008. http://www.fda.gov/cder/foi/label/2008/021588s024lbl.pdf; FDA approves Gleevec to prevent recurrence of rare gastrointestinal cancer [press release]. FDA News 2008 Dec 19. http://www.fda.gov/bbs/topics/NEWS/2008/NEW01931.html.